overhead valve- camshaft installed in engine block, valves are operated through lifters, pushrods, and rocker arms. outdated, bad timing at high rpm, simple, durable. difficult more than 2 valves.
OHC or COHC
overhead cam- camshaft installed in the cylinder head, valves operated directly through lifters. valves operated almost directly by camshaft, requires timing bolt or chain, easy perfect timing at high rpm. possible 3-4 valves
DOHC or Twin Cam
double overhead cam- mostly in new cars (w/ 2cams). more complex/expensive. produce more power w/ smaller engine volume. adopt variable timing.
a rotating shaft within the engine that opens and closes the intake and exhaust valve in the engine
Turns the piston's up and down motion into circular motion
an old term for an electric generator that produces alternating current (especially in automobiles)